Giacomo Fabris, Andrea Nicoletto March 18, 2020 Download PDF version at: https://archive.org/details/contact-tracing-covid 1 Background If you opened a newspaper in the last month you may want to skip this chapter. It is well known that in late 2019 a new virus, SARS-CoV-2, emerged in the city of Wuhan, China[1]. The virus infects…